Plug contactor



Jan. 30, 1968 KAROL 3,366,917

PLUG CONTACTOR Filed Oct. 15, 1965 United States Patent ABSTRACT OF THEDISCLOSURE A flexible insulating shroud for a plug contactor wherein theshroud has a series of serrations to facilitate manual grasping and hasa pair of conical sections to provide strain relief.

This invention relates to plug contactors of the type used, for example,in plugboards for automatic computers, tabulators, accounting machinesand the like for completing selected electrical circuits to control theoperation of the machine as desired, and more particularly to a new andnovel shroud or jacket for such contactors.

In normal use plug contactors are subjected to a great number ofinsertions and withdrawals from a plugboard. During the withdrawal ofsuch contactors from a plugboard it is desirable to have the operatorgrasp the shroud proper to effect the withdrawal. However, in order toeffect a more rapid operation, the operators will frequently merely pullon the wires leading to the plug contactors and effect the withdrawal inthis manner. So long as the wires are pulled at right angles to theplugboard, there is no problem; however, as often results, the wires arepulled at a sharp angle to the board and, therefore, create greatbending stresses in the region where the wire connects with thecontactor. If this procedure is repeated a sufiicient number of times,there is the possibility of the wire fraying and thus destroying theelectrical connection.

It is therefore an object of this invention to provide a new andimproved shroud for plug contactors whereby the possibility of frayingthe wires is materially reduced.

Another object is to provide a shroud having means which facilitatesgrasping the contactor directly for insertion or withdrawal.

Other objects and attainments of the present invention will becomeapparent to those skilled in the art upon a reading of the followingdetailed description when taken in conjunction with the drawings inwhich there are shown and described illustrative embodiments of theinvention; it is to be understood, however, that these embodiments arenot intended to be exhaustive nor limiting of the invention but aregiven for purpose of illustration in order that others skilled in theart may fully understand the invention and the principles thereof andthe manner of applying it in practical use so that they may modify it invarious forms, each as may be best suited to the conditions of aparticular use.

In the drawings, in which like reference numerals refer to like parts:

FIGURE 1 is a perspective view of a plug contactor showing a preferredembodiment of the present invention,

FIGURE 2 is a side elevational view of the plug contactor shown inFIGURE 1, and

FIGURE 3 is a side elevational view similar to FIG- URE 2 but showing analternative form of shroud.

The plug contactor comprises an outer sleeve member 2, as seen in FIGURE1, and a nose portion 4 terminating in a nose member 6. A pair ofradially extending latch portions 8 extend from the outer sleeve and arepositioned to be engaged behind a rearwardly directed face of aplugboard into which the contactor is connected. A wire conductor 10 isconnected to the plug 3,366,917 Patented Jan. 30, 1968 member and aninsulating shroud or jacket 12 of plastic or the like surrounds theconnection. For a more complete disclosure of the manner in which thewire conductor is connected to the plug member, reference is made to US.Patent No. 3,134,633 issued May 26, 1964, and assigned to the assigneeof the instant application.

Referring to FIGURES 1 and 2 the shroud 12 is seen to comprise acylindrical portion 14 which surrounds that portion of the plug and Wireconductor where the connection has ben effected. Integrally formed withthe cylindrical portion 14 is a first tapered section 16, said taperedsection extending substantially beyond the end of the forward part ofthe plug contactor. A series of serrations 18 are formed in the shroudin order to facilitate grasping of the shroud for inserting the pluginto or withdrawing it from the plugboard. It is to be noted that thediameter of the shroud adjacent the serrations 18 is substantially lessthan the outer diameter of the cylindrical portion 14. Therefore, notonly does the serrated portion serve the function of facilitatinggrasping but further provides a reduced diameter section wherein bendingof the shroud can readily occur. If the shroud was ended at this point,it can be seen that the majority of the bending of the shroud duringpulling on wire conductor 6 at an angle to the plugboard would beconfined to that area immediately adjacent to the serrations. In soconfining the area over which the bending of the wire takes place, thereresults a sharp radius which is objectionable in that sharp radiiproduce extreme stresses which are quite likely to damage the wireconductor. To avoid this situation, a second tapered section 20 isprovided, which section terminates in a portion of substantially reduceddiameter. By providing this second tapered portion, the radius ofcurvature of the bending of the wire is significantly enlarged and thestresses on the wire are distributed over a substantial length of wire.The wire conductor 6 can now be bent and pulled an indefinite number oftimes without resulting in any damage to the conductor.

FIGURE 3 shows an alternative embodiment of the invention wherein theshroud 22 comprises a cylindrical portion 24, identical to cylindricalportion 14 previously described, and a long tapered portion 26 having aseries of serrations 28 disposed therealong. As can be seen from thefigure, the serrations 28 decrease in size to follow the angle of thetaper 26. In this embodiment it can be seen that the serrations 28provide a grasping means over a substantial length of the shroud. If thewire conductor 6 is pulled or bent at a substantial angle to theplugboard, the bend will be taken up over the entire length of taper 26and serrations 28 thereby establishing a considerably large radius ofcurvature with the result that the bending stresses are spread over asubstantial portion of the wire. As in the previous embodiment, theconductor 6 can now be bent and pulled an indefinite number of timeswithout damage to the conductor.

It can therefore be seen that the objects of the invention have beenachieved in that a shroud for a plug contactor has been produced whichwill permit the conducting wire to be pulled at any angle to a plugboardwithout any danger of damage to the wire.

Changes in construction will occur to those skilled in the art andvarious apparently different modifications and embodiments may be madewithout departing from the scope of the invention. The matter set forthin the foregoing description and accompanying drawings is offered by wayof illustration only.

I claim:

1. In a plug contactor wherein a wire conductor is connected to a plugelement, a flexible insulating shroud comprising a cylindrical portionsurrounding the connection between said plug element and said conductor,a first strain relieving portion extending from said cylindrical portionand being a frustum of a right circular cone, a serrated portionextending from said first strain relieving portion for facilitatingmanual grasping of said plug contactor, said serrated portion comprisinga plurality of annular rings of substantially equal diameter, saiddiameter being less than the external diameter of said cylindricalportion and greater than the minimum external diameter of said firststrain relieving portion, and a second strain relieving portionextending from said serrated portion and being a frustum of a rightcircular cone, said second strain relieving portion having a maximum andminimum external diameter smaller respectively than the maximum andminimum external diameters of said first strain relieving portion andbeing of greater axial extent along said conductor than said firststrain relieving portion.

References Cited UNITED STATES PATENTS 15 RICHARD E. MOORE, PrimaryExaminer.

